1. Field of the Invention
The present invention generally relates to a magnet switch for a starter used to start internal combustion engines.
2. Related Art
Japanese Patent Application Laid-open No. 4-303521 discloses a magnet switch for starter, wherein an exciting coil is wound around a bobbin, and a rod extends integrally to the rear end of a plunger arranged in this bobbin. A sub-movable contact (first movable contact) fixed with insulating mold material and a main movable contact (second movable contact) fixed with insulating mold material are arranged over this rod, and a pair of fixed contacts are set to oppose the sub-movable contact and main movable contact. The sub-movable contact and main movable contact are press-fit by a contact springs set over the rod on the fixed contact side. The sub-movable contact has a large electrical resistance and the main movable contact has a small electrical resistance.
With this structure, the plunger is attracted when the exciting coil is energized, and the sub-movable contact with the large electrical resistance directly contacts the fixed contact first to slowly rotate the motor. When the plunger is further attracted, the main movable contact with small electrical resistance directly contacts the fixed contact to rotate the motor at full-force. This allows the engagement of a motor pinion and an internal combustion engine ring gear to be improved.
However, with the above starter, the first movable contact and second movable contact directly contact the fixed contact in two steps, so separate contact springs are required for the first movable contact and second movable contact. The number of contact springs increases thereby increasing the number of parts.